Have you had this problem before? I did a load calc for a whole house generator and it came to 107 amps. The Main panel in the cabin/house is 100 amps. The generator was going to be at the meter pedestal that is 75 feet from house. I did not want to have to trench for any load shedding.
Generator Larger than service
- Thread starter arnettda
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- Occupation
- Licensed Electrician
Do the load calc again, use the optional method. It takes a lot of work to get over 100A.
Does the house have electric heat?
Does the house have electric heat?
No Electric Heat, But it is 3257sq feet, Elec dryer and water heater, 3 ton AC unit besides the main stuff most houses have. I added in the fridge but can I leave that out and assume the two small appliance circuits will cover it.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
A generator might be larger than the service because the generator must have the capacity to handle starting loads for motors and other devices with high initial inrush.
Because an outage might stop all these loads, a generator needs to be able to handle multiple inrush loads at the same time, since it may need to start several of these loads when it picks up.
A service can depend on the higher capacity from the POCO for these loads, and the time delay inherent in its main breaker, as well as a lower probability that they will all start at the same time.
Because an outage might stop all these loads, a generator needs to be able to handle multiple inrush loads at the same time, since it may need to start several of these loads when it picks up.
A service can depend on the higher capacity from the POCO for these loads, and the time delay inherent in its main breaker, as well as a lower probability that they will all start at the same time.
ceb58
Senior Member
- Location
- Raeford, NC
What size is the generator?
mgookin
Senior Member
- Location
- Fort Myers, FL
- Occupation
- Retired inspector, plans examiner & building official
You have a 3257 sf house with a 100 amp service?
Yes, One large older house with two big additions, one on each end.
mgookin
Senior Member
- Location
- Fort Myers, FL
- Occupation
- Retired inspector, plans examiner & building official
Sounds like your predecessors were not doing load calcs as they expanded that system.
Maybe sell them a service upgrade...
- Occupation
- Licensed Electrician
This is a house being discussed. How much inrush can there be?
I have 3000 sqft house, electric double oven, two electric dryers, no A/C. If I turn every thing on, including counter top appliances and plugging in hair dryers I barely pull 80 Amps.
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kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
You should not size a generator based on amps, it should be done using load data; including power factors. Sequencing of starting loads is vital in understanding proper sizing.
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